The present invention relates to a color display such as a color liquid crystal display and a color electroluminescent display.
A prior art electroluminescent display 51 shown in FIG. 4 includes an electroluminescent layer 58, which contains an organic electroluminescent material. The organic electroluminescent material contained in the electroluminescent layer 58 is degraded when contacting oxygen and hydrogen. Therefore, the electroluminescent layer 58 is accommodated in a space defined by a substrate 52 and a sealing case 60. Getter agent 60a is provided in the sealing case 60. The getter agent 60a contains at least one of absorbent, desiccant, and oxygen adsorbent.
The electroluminescent layer 58 is provided between the transparent electrodes 57 and a metal electrode 59. The display 51 also includes thin film transistors 56. Each transparent electrode 57 is electrically connected to one of the thin film transistors 56. Therefore, parts of the electroluminescent layer 58 that correspond to the transparent electrodes 57 function as active matrix electroluminescent elements.
The electroluminescent display 51 includes a color filter 53. The color filter 53 includes filter elements 53b each of which changes white light to red light, green light, or blue light. Each filter element 53b is aligned with one of the transparent electrodes 57 with respect to the thickness direction of the electroluminescent display 51 (the vertical direction as viewed in FIG. 4). White light emitted from each electroluminescent element is changed to red light, green light, or blue light by the corresponding filter element 53b. The light is then outputted through a substrate 52.
To improve the contrast of a shown image, a black matrix 53a is generally provided between each adjacent pair of the filter elements 53b. However, the black matrixes 53a can decrease the open area ratio of the electroluminescent display 51. This is because the black matrixes 53a are often formed relatively large in consideration that each transparent electrode 57 may be displaced relative to the corresponding filter element 53b when the color filter 53 is mounted on the electroluminescent display 51.
Japanese Laid-Open Patent Publication No. 10-255986 discloses an electroluminescent display shown in FIG. 5. In the electroluminescent display of FIG. 5, an electroluminescent layer 58 is provided between transparent electrodes 57 and a translucent electrode 62. A conductive black layer 63 is provided at the back of the translucent electrode 62.
When a user looks at the electroluminescent display 51 of FIG. 4, light reflected by portions of the metal electrodes 59 corresponding to portions of the electroluminescent layer 58 emitting no light are within sight of the user. This makes it difficult for the user to view an image on the screen. In contrast to this, the electroluminescent display of FIG. 5 does not have such drawbacks. However, the black matrixes on the color filter can decrease the open area ratio.
Japanese Laid-Open Patent Publication No. 2000-48964 discloses an electroluminescent display shown in FIG. 6 and an electroluminescent display shown in FIG. 7. Each of the electroluminescent display has transparent electrodes 57, metal electrodes 59, and electroluminescent layers 58 located between the electrodes 57, 59. A black layer 63 is provided at the back of the metal electrodes 59. In the electroluminescent display of FIG. 7, an auxiliary electrode 65 is provided at each of the metal electrodes 59.
In the electroluminescent displays shown in FIGS. 6 and 7, parts of the black layer 63 corresponding to each adjacent pair of the electroluminescent layers 58 function as black matrixes. Therefore, unlike a case where separately formed black matrixes are provided on a color filter, the open area ratio is not decreased due to the black matrixes. However, the electroluminescent displays shown in FIGS. 6 and 7 are of a bottom emission type, which outputs light emitted by the electroluminescent layer 58 through the substrate 52. The substrate 52 therefore must be of a light transmittance type. Compared to a top emission structure in which light emitted by the electroluminescent layer 58 is outputted without passing through the substrate 52, the bottom emission structure is likely to decrease the opening area ratio.